<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<p id="help">Helpful notes will appear here</p>
<p>E-mail: <input type="text" id="email" name="email"></p>
<p>Name: <input type="text" id="name" name="name"></p>
<p>Age: <input type="text" id="age" name="age"></p>


</body>
<script type="text/javascript">
    window.onload = function () {
        function showHelp(help) {
            document.getElementById('help').innerHTML = help;
        }

        function setupHelp() {
            var helpText = [
                {'id': 'email', 'help': 'Your e-mail address'},
                {'id': 'name', 'help': 'Your full name'},
                {'id': 'age', 'help': 'Your age (you must be over 16)'}
            ];

            for (var i = 0; i < helpText.length; i++) {
                var item = helpText[i];
                document.getElementById(item.id).onfocus = function () {
                    showHelp(item.help);
                }
            }
        }

        setupHelp();
    }

</script>
</html>